1. Field of the Invention
This invention relates to apparatus for inspecting malformed coupling elements from slide fastener chains.
2. Prior Art
Coupling elements of a discrete type are susceptible to malformation or otherwise irregularity while in corner rounding. These problems are due to tension being not constantly applied onto a slide fastener chain passing through a chamfering device. In such instance, the coupling elements tend to disposed in that device, leading to excessive rounding at either one corner portion. Acceptable coupling elements have their corners rounded at a uniformly slight travel.
Certain apparatus have been proposed to detect malformed coupling elements. One such apparatus is directed to visually inspecting finished slide fasteners as disclosed for instance in Japanese Patent Publication No. 61-94606. This prior apparatus, however, is not wholly satisfactory from the accuracy point of view because visual inspection varies with the operator's skill and concentration and also with his or her fatique, sometimes inviting oversights. Detecting slide fastener products one at a time entails labors and time burdens. Japanese Patent Laid-Open Publication No. 59-32124 teaches an optical inspection with use of laser beams which however calls for costly, spacious apparatus.